Friction spring brake



Oct. 20, 1931.

M. HARRIS 1,828,367

FRIQTION -SPRING' BRAKE Filed Deo. 20, 1926 2 lsheets-sheet 1 L I" l JO 642 Oct. 20, 1931. M, HARRlS 1,828,367

FRICTION SPRING BRAKE Filed Deo. 20, 192s '2 sheets-snee; 2

Patented Oct. 20, 1931 i 'entren STATES! writeNr'N 'man nanars; or DETROIT; niermann,

narco rnonncrs CORPORATION, or DAYTON, onid-nlconronn'rronf WARE ASSIGNOR, BY- MESNE' ASSIGNMENTS; OFY DELA- ERICTION" SPRING BRAKE rlhis invention relates to an energy absorbing device designed primarily asa spring brake or sho'clr (absorber, (hereinafter referred to as a spring brake), to be interposed between tWo spring-connected members of a vehicle for controlling excessive spring movements occasioned by irregularitiesin road- Way surfaces, and particularly energy absorbing devicesembodying;` in their organi ffm sation a friction surface drum mountedfupon w suitable operating means,

. one of the spring-'connectednnembers, for instance,l the springV supported franieof a chassis, andan expansible brake' band oscillated, in contactfwith such surface, by

for instance, a

radial arm connected to the other of the spring-connected members, forjinstance, the axle; and the said invention embodies certain novel conditions inits operative principle and ,3m in its construction, amongvvhich are the following: -Y Y i The elimination of the central spindle and fixedV bearing therefor heretofore. employed in connection Withthe expansible band type of spring brake, and consequent reduction of the organization to a simple construction ire,- quiring Vno lubrication; this novel condition being realized by employing the frictional bearing of the brake band on .the drum as the centeringand supporting bearing forthe oscillatory operating means, lfor instance, the aforesaid radial operating arm and a yoke connecting said arinto the brake band; in other Words,by floating'` the center of. oscilla; tion Within the drum through meansof the brake band, and having all thrust incident to movementof the brake band by the operating arm, received on the friction surfaces Whichrequire'no lubrication, and in a manner to amplifyl frictional resistance as distinguished from fixing the center of oscillation in', and having thrust taken up by voutsidebearings. Which `detract Vfrom frictional resistance and render the life and continued functioning of the device subject to the supply ofv lubricant to such bearings also Having the frictional resistance to oscillatory movement developed by .the friction band automatically, Without the interarll except circumferential position of cams, toggle levers, orother posi,- tive spreadingmeans in the connection be-V tween the foperating arm andfthe brake band, thereby not only simplifying: the connection between the operating, arm andr the, brake band, but adapting the brake bandto assume different initial: positions of, revolution relatively to thedrum, to correspond` With various initialdepressions ofthe spring under. theiload whichitcarrieaand toloperate from anysuch initial position; namely, by having the brake bandiconstructedgwitjh alfree,resilient end? portion beyondY its connection with the oscillating means, and-particularly the .end which constitutes the leading portion ofthe brake band during those movements vvhich-correspond to rebound of the spring, and preferably `embodying the same conditionin, that end .of the brake band which leads in movements corresponding` to spring A compression; and having the inherent resiliency Ofsuchleading portionor portions act ingy inthe direction to initiatel frictional bearing against the drum, sothat the leading portionl develops a. drag, frictionalaresistance, or reluctance torotatiorn which, under thrust imparted to thebrake band in rear ofY such leadingportion, causes thevbrakeband as a` Wholev to expand and increaseitsffrictional resistance, and `causes this result to. follow in varyin degrees proportionalV to the suddenness o therotary moveinent and therefore proportional to the violence of energy Whi'chis tobe resisted; also.

Having means for increasingv the reluctance or drag of` the leading endV or endsof the brake band over that developedby its, or their., .normal inherent resiliency, such means comprisingeither or bothlof twb expedients, and one or another of severalfdifferent ar? rangements thereof, to-vvit: reinforcing resilient meansA acting radially against the leading portion or portions; or a, friction shoe in sliding. Contact with the drum and inthe path of the leading Vendso that theleading end impinges against it and has-thedrag of the shoe addedrto the drag lof the leadingend in developing the reluctance or resistance which `expands the bandas a Wholasaid` shoe serving, if desired, for either leading end,

alternately, by having it interposed between said ends; or having the auxiliary resilient means ac.ing directly upon and increasing the frictional drag of the shoe, and thus indirectly upon the leading end or ends; also Adapting a spring brake of the kind described, and particularly when provided with a reinforcing friction shoe, to limit the interposition of its braking influence, or at least braking influence of a substantial order, to those spring movements which are of suflicient amplitude to render braking influence desirable, so that all those movements resulting from minor road inequalities which are largely absorbed in the axle, and transmission of which to the body would bc objectionably increased by substantial braking resistance at the time, will be left'without substantial resistance; but any amplitude of spring compression o1r spring reaction, o r both, exceed'- ing a predetermined order, will automaticab ly call into play a substantial braking in fiuence and one corresponding to the severity of the force to be controlled; this result being attained automatically by the very simple expedient of introducing, between the friction shoe and the leading end or leading ends of .the biake band, lost motion of such diinension that all those oscillatory motions transini ted through the radial arm by unobjectionable vibrations of the spring, will be opposed only by the normal braking influence of the band alone, and with the low coefliciency of friction incident to such slight movements; but whenever the spring compression, or the reaction of the spring from compression, exceeds the predetermined minor range, the friction shoe will be picked up by the leading end and the braking resistance will be of a substantial order appropriate to the an'lpltude of spring movement since it results from the drager reluctance of the leading end and friction shoe combined which, being automatically built up according to suddenness of movement, will be commensurate with the energy to be absorbed; also The provision of means for establishing angularly flexible articulation between a radial operating arm, Athrough which the band is oscillated, and the axle or other spring-connected part to which it is to be united, without involving metal to metal contact between joints, and therefore, without the necessity of lubrication in keeping the parts properly cperatiif'e; this condition being realized bv introducing between the radial arm and an element to which it is to be connected, for instance, a bracket attached to the vehicle axle, a rod passing through openings, substantially larger than the rod, in both the arm and the bracket and completing a wrist joint connection between the rod and each member through which it passes, by means of resilient material surrounding the rod on oppsite sides of the member and extending between the rod and the sides of the opening, or otherwise spacing said metal portions apart; the resilient material being held under desired initial compression by appropriately spacing abutmeiits by which it is fixed upon the rod.

Other distinguishing characteristics of the invention, as well as the structural details of two alternative embodiments thereof, will be readily understood from the following description when taken in connection with the accompanying drawings, in Which- Figure 1 is a side elevation of one form of the invention, shown partly in cross-section to disclose the construction of the means for articulating the operating arm and the axle of the vehicle;

Figure 2 is a cross-sectional View of Figure l taken on line Qtr-2m looking from above;

Figure 3 is a side elevation, partly in crosssection, similar to Figure 1 but of a modified form of the invention and with the angularly articulating means omitted;

Figure 4L is av view similar to Figure :2 taken on line Lla-#las of Figure 3; and

Figure 5 is a cross-sectional view taken on line 500e-5m of Figure 1.

Referring to the form of the invention illustrated in Figures 1 and 2, which embodies a spring brake to be introduced between two spring-connected vehicle members such as a chassis frame 1 and axle 2, the drum 3 is rigidly attached to the chassis frame and is provided with a friction surface, such as at ll, adapted to receive in frictional bearing, an expansible brake band 5 which is composed of a metallicring 6 and a facing of frictional material, shown at 7 attached to its outer surface by suitable means, such as rivets 8, the band having inherent resilience so as to bear with an initial pressure against the drum surface. Brake 'band 5 is provided with spaced ends which are resilient and free to press against the drum and said ends are bent to form abutinents 9; and it has attached to it, at points remote from its ends, the means through which its oscillation is controlled, to wit: the arms of a. yoke 10, such attachment being preferably accomplished by riveting a portion 11 of the band to the feet 12 as shown at 13.

The yoke is provided with a centrally disposed hub 14 which projects laterally from the side of the drinn, and receives the operating arm 15, by engaging in the seat provided on the arm at 16, the arm being held rigidly on the hub by the bolt 17, and prevented from rotating thereon by the non-circular form of the meeting surfaces, and by the driving fit of the shank 19fof the bolt, in the central opening of the hub. Through this means, the elements, for instance, the radial arm and its connecting yoke, by which movement of the band is controlled, have no positioning or guiding caring other than that develmessage' pedE bythe frictionalV bearing of; the 1 band y The yoke=isfurther provided with a--seat 20? whicli is adapted to receivey onefend1v of a coiled spring 2l, the other end of which is received in a socket 22 inl a frictionshoe 23'; Shoe 23 is positioned in frictionalbearing with the surface of the' drum andl between, and therefore intlie paths of,fthe abutments 9: of the brake band, the length ofthe shoe being" less than the space between said a'butments, thereby developing lost motion in the pick-up ofthe shoebythe leading end of the band; The shoe isfurther provided with a frictional surface, which visjshown; lat 24, which -hasa'l higher coefiiciency of friction than that of the facing 7 on the brakelband; By the meansjust described, auxiliary frictional resistance isprovided for the ends of the band and for amplfying braking eiiect; said` resistance is reinforced by radially acting resilient means, and the lost motion insures desiredl restriction of the amplified braking effect' to spring disturbances of the majororder.

Over the open end of the drum isplaced a closing cap 25 which is provided on its outer edge with aV flange'26 adapted-to telescope with" the sides ofthe drum,` the bottom of the flangebeing bent outwardly, as at 27, to form a second iiange or ledge through which to hold the cap in place. The outer cylindrical surface' of theV drum is provided with a groove 28 and isadaptedv to receive one edgeV -v of they split ring 29 of Uf-sh'aped cross-section, positioned aroundthe drum, the other edge of which' engages the flange 27 ofthe cap' 25` solas to lock it in position. The split ring 29 has packing 30 placed therein for sealing the crack between flange 26 and the drum, against passage of dirt or moisture to the' interior ofthe brake.v The split ring 29 is clamped in position by the bracketsBl on tlieendsof therin'g, having. bentends32 perforated to receive thebolt' l33 in the manner shown, so that by turning up the nut 34, the'parts maybe lo'c'kedfin cap-securing and sealing relation. Cap 25 is provided centrall'y with an opening 35, larger in diameter than ythe hubV of the yoke, and permitting passagefof the hub withv clearance on all sides. This opening is likewise sealed against the admission of moisture anddirt, by the packingvringsV 36 and 37, positioned on the inner and outer sides of the closing plate 25, in a mannerto be maintained vby the oscillated braking' element in 'proper position; said packing rings 36 and 37 being positioned, the

onebetween: the shoulder 38 on the yoke and inner face ofthe cap, and thev other between the ra'di alarm 15, or Vwasher 39T and the outer face of the cap, as shown in Figure l.

Figures 3 andv 4V show an embodiment of the invention withthe radial resilient means, directly acting upon and reinforcingthe leadiirthe `modification rst described, butI in this instance,.,the` brake band 43 mounted' on the Varms i ofr the-yoke has its friction s' surface dividedfinto-three sections, such as shown at 40, 4l and 42, all rigidly attached to and adapted f tomove with' thebrake bandlwhenthelatter is driven by thefyoke; The'leadingends of the brake band areresiliently. pressed into frictional' bearing'against the surface of" the drum by coiled`- springs 44 andV 45 seated on theyoke,"as at' 46 and 47, the yoke, arm, band and springs all movingI together. In this instance, the material selected for the friction facings and 41 is Vof a higher coefliciency of? friction-than facing 42 so as to cause greater frictional resistance to movement at thetwoends, whichy become leading ends of the brake band depending upon the direction of movement. Y

In either form of the invention, the means employed for articulating the radial operating arm 4S or 48a with the axle of the vehicle,

`is that-shown ,in Figure' 1, and comprises an enlarged eye at the outer end of the arm, such as shownat 49, a rod adapted to be positioned in the eye 49 and provided with screwthreads 5l and 52 to receive the nuts 53 and on oppositesides of said eye, and adjustably sustaining Washers and 56 which support a resilient motion transmitting memberV 57 surrounding the rod andfdistributed on opposite sides of the eye; such resilient transmitting member being conveniently though not necessarily made in` the form of two resilie-nt blocks 57al and 58a. ItV has shoulders 58 through 'which it bears against opposite sides of the arm when compressed by the nuts and washers, and thus serves to resiliently transmit axial movement of the rod to the arm while permitting freedomv of angular movement between them, further flexibility being provided for by the elongation 64 in the rodopening which permits the radial arm to move in an arc while connectedl to the axleconnected bracket, which bracket moves in substantially a straight line, some of the relative movement being taken up in the bodily movement of a part of the resilient mass whereas the remaining movement is eected by distorting other parts of the resilient mass. The transmitting member 57 may be provided with a circular bore'of greater diameter thanthe rod 50', and it includes a portion within the: eye 49, forming a spacing element between the metal parts. The i'exibility of this connection varies according to initial compression of the resilient transmitting member57 and such compression is determined at will by adjustment of the nuts 53 and 54. The lower end of the rod is connected to the bracket 59 by a similar nonmetallic resilient and angularly flexible connection 60 likewise capable of adjustment, by confining nuts 53, 54a. Bracket 59 has a jaw 6l rigid thereon, withagroove adapted to engage one flange of the axle 2, a aw 62 sliding thereon, with a groove to engage an opposite flange of the aXle and a nut 63 threaded on its outer end and adapted to press the two aws together.

The operation of the modification of my invention shown in Figures l and 2 is as follows: Under ordinary running conditions, relative movement of the axle 2 and the chassis frame l will be slight and only minute movements will be transmitted to the radial arm 4S by the connecting rod 50, and only correspondingly slight oscillation will occur in the yoke 10, and these being relatively slow and being resisted only by the leading end, will meet with slight braking resistance. The yoke 10 and the radial arm 4S by virtue of their construction have only a floating center of oscillation; the friction surface of the drum alone will serve as their guiding bearing; and all thrusts occasioned by movement of the axle 2, relatively to chassis frame l, will be imparted directly to said friction surface. But when excessive movements occur between the axle and chas'is frame and the oscillation of the brake band is amplified, the leading end of the band not only builds up its own resistance by the suddenness of the movement but it adds the resistance of the friction shoe 24 so that the now relatively great reluctance of the leading end causes an increased expansion in the ha nd, and a builtup frictional resistance commensurate with the energy to be absorbed. The spaces between the ends of the friction shoe and the abutments 9 of the brake band may be of any suitable measurement, the distance varying with different installations.

Referring now to Figures 3 and fl, in operation the device is similar to thatof the modification first described, so far as concerns slight resistance to spring movements of minor amplitude and substantial curbing of movements of objectionable amplitude and force, but the leading ends alone, reinforced by the radial springs, are depended upon to produce the results; the band being adapted to develop slight resistance under slow and short movements of the spring, and large braking forces under excessive action thereof by having the band equipped with a special character of facing material, forinstance, smooth surface chrome-tanned leather, at the leading ends which will afford great coeffi- 'ciency of friction under sudden movement and with a coarser leather that will have a low initial coefficient of friction over the remaining portion.

Leases? The above detail description and disclosure in the drawings illustrate the preferred embodiments of'the invention, but it is to be understood that the invention includes all modieations that fall within the scope of the appended claims;

I claim: l

l. In-an energy absorbing device, comprising a drum member, .and a band member relatively rotatable and in frictional bearing with each other, a' friction shoe also in frictional bearing with the drum member, in the path of the brake member, and adapted to be moved by and have its frictional resistance added to that of the brake member, in either direction of relative rotation of the said members.

'2. In an energy absorbing device, comprising a drum member, and a band member relatively rotatable and in frictional bearing with each other, a friction shoe also in frictional bearing with the drum member, in the path of the brake member, and adapted to be moved by and have its frictional resistance added to that of the brake member, in either direction of relative rotation of the said members, there being lost motion between the brake shoe and the band member, which permits the band member to act independently' of the brake shoe during a limited portion of the relative rotation.

3. In an energy absorbing device, comprising drum member and a split band member having spaced ends, said members being in frictional bearing one with the other and relatively rotatable in opposite directions, a brake shoe interposed between the ends of the band member and in frictional bearing with the drum member and adapted to engage either end of said band.

ff. In an energy absorbing device, comprising a drum member and a split band member having spaced ends, said members being in frictional bearing one with the other and relatively rotatable in opposite directions, a brake shoe interposed between and .adapted to engage the ends of the band member and in frictional bearing with the drum member, there being lost motion between the brake shoe and the band member in each direction of relative rotation between the members.

5. In an energy absorbing device, a drum member, and an expansible band member in frictional bearing one with the other and relatively rotatable, the band member having a resilient, free leading portion in either direction of rotation normally developing frictional resistance to movement and building up expansion in the band member, .and a brake shoe also in frictional bearing with the drum member, in the path of said lleading portion, and adapted to add its frictional resistance to that of said leading portion.'

6. In a double acting energy absorbing device, a drum member, an expansible band member split and having its ends spaced apart, said members being in frictional bearing one with the other and being relatively rotatable, and the spaced endslof the band member beingradially resilient and free to expand and develop initial frictional resistance to movement upon the drum member, and a brake shoe interposed between said ends, also in frictional bearing against the drum member, andadaptedto add its frictional resistance to that of either end of the brake member.

7. In an energy absorbing device, a drum member, an expansible band member in frictional bearing with said drum member, means for developing relativerotation between said members, a brake member having a resilient, free leading portion normally dev veloping initial pressure against the drum member and causing expansion in the band by frictional resistance thereof, and automatic means increasing the frictional resistance of said resilient end portion in either direction of rotation.

8. In an energy absorbing device, a drum member, an expansible band member in frictional bearing with said drum member, means for developing relative rotation between said members, a brake member having a resilient, free leading portion normally developing initial pressure against the drum member and causing expansion in the bandv by frictional resistance thereof, and automatic means increasing the frictional resistance of said resilient end portion in either direction of rotation comprising radially acting spring means. 1

9. In an energy absorbing` device, a drum member, an eXpansible band member in frictional bearing with said drum member, means for developing relative rotation between said members, a brake member having,

a resilient, free leading portion normally developing initial pressure against the drum member and causing expansion in the band by frictional resistance thereof, and automatic means increasing the frictional resistance in either direction of rotation of said resilient end portion comprising a brake shoe in the path of said end and also in frictional bearing with the drum member, and a radial spring acting against said brake shoe.

10. In an energy absorbing device, a drum member, an expansible'band member in frictional bearing with said drum member, said members being 'mounted for relative rotation, a yoke member connected with said band member and controlling thewsame in said relative rotation but leaving an end of said band member free and unrestrained in its pressure against the drum member, a brake shoe in frictional .bearing with said drum member and in the path of said free end, and resilient means sustained by the yoke and acting radially against saidbrake shoe to increase its frictional resistance to movement by theband member.

11.' In an energy absorbing device, a cylindrical member, braking means in frictional bearing with said cylindrical member and including a split band, an oscillatory yokeconnected with said split band remotely from the ends of the band, having its center of oscillation determined by the braking means alone, and radially acting resilient means located between said yoke and a portion of the braking means at a point remote from the connection of the yoke to the band.

12. In an energy absorbing device, a drum member, a band member in frictional bearing with said drum member, a cap member forming a closure for said drum member and including a flange telescoping with a cylindrical wall of the drum member,'and a clamping ring surrounding portions of the cap, flange. and drum, and interengaging with each vof them in the direction of telescoping movement to hold them against separation.

13. In an energy absorbing device, a drum member having a cylindrical wall, a band member within said Vdrum member, a cap member having a flange telescoping with the cylindrical wall of the drum member, the flange of the cap and the cylindrical wall of the drum member being each shouldered for engagement in the direction of telescoping movement, and a vclamping ring embracing portions, respectively, of said cylindrical Wall andV flange and having inturned lips interlocking with the shoulders thereof.

14. In an energy absorbing device a member having a friction surface and a flexible friction member having inherent expandingA resilience adapted to engage said surface to frictionally resist relative rotation therebetween, means connecting said friction surface to one element and said friction member to a second element, between which relative movement takes place, said means being conn structed to confine the relative `movement between said friction surface and said friction member to relative rotary movement by means of their frictional contact only, said frictional contact extending throughout the entire surface of said friction member.V

r15. In an energy absorbing device a fric-` of December,.1926. v

n MARK HARRIS. 

